1. Field of the Invention
The field of the invention relates to adjustable lumbar supports, particularly for motor vehicle seats.
2. Brief Description of the Prior Art
Many motor vehicle seats are today equipped with manually-operated or electrically driven lumbar supports. Such supports provide superior comfort, particularly during long drives. The adjustability of the lumbar supports allows each driver or passenger to provide the necessary curvature therein to suit his individual needs. U.S. Pat. Nos. 4,354,709 and 4,452,485 disclose a support structure including adjustment means for varying the curvature thereof through the use of a pair of opposing belts and means for bowing one set of belts with respect to the other.
Another type of lumbar support includes a series of three vertically oriented bands and a series of horizontal ribs secured to two or more of the bands. The middle band is secured at one end to a tensioning device while the two other bands are secured at both ends to substantially fixed supports. When the middle band is tensioned, both it and the two adjacent bands will bow, thereby providing the desired curvature to the portion of the seat to which it is secured. The effort required to increase the tension of the middle band increases as the curvature of the support increases.